Rotary union with expanding ring

ABSTRACT

The disclosure describes a rotary union that includes a housing, a rotating machine component supported in the housing, a rotating seal member associated with the rotating machine component, a non-rotating seal member slidably and sealably disposed within the housing adjacent the rotating seal member, an expandable seal disposed between the non-rotating seal member and the housing, and an internal clamp disposed within an end portion of the expandable seal such that the end portion of the expandable seal is compressed between the internal clamp and the bore of the housing.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/289,659, filed on Feb. 1, 2016, which isincorporated herein in its entirety by this reference.

TECHNICAL FIELD OF THE DISCLOSURE

The present invention relates to rotary devices such as rotary unions,swivel unions, slip rings and the like.

BACKGROUND OF THE DISCLOSURE

Fluid coupling devices such as rotary unions are used in industrialapplications, for example, machining of metals or plastics, workholding, printing, plastic film manufacture, papermaking, and otherindustrial processes that require a fluid medium to be transferred froma stationary source such as a pump or reservoir into a rotating elementsuch as a machine tool spindle, work-piece clamping system, or rotatingdrums or cylinder. Often these applications require relatively highmedia pressures, flow rates, or high machine tool rotational speeds.

Rotary unions used in such applications convoy fluid medium used by theequipment for cooling, heating, or for actuating one or more rotatingelements. Typical fluid media include water-based liquids, hydraulic orcooling oils, air, and others. In certain instances, for example, whenevacuating media from a fluid passage, rotary unions may operate undervacuum. Machines using rotary unions typically include precisioncomponents, such as bearings, gears, electrical components, and others,that are expensive and/or difficult to repair or replace during service.These components are often subject to corrosive environments or todamage if exposed to fluid leaking or venting from the rotary unionduring operation. Fluid leaking from a union is also typicallyundesirable.

A rotary union typically includes a stationary member, sometimesreferred to as the housing, which has an inlet port for receiving fluidmedium. A non-rotating seal member is mounted within the housing. Arotating member, which is sometimes referred to as a rotor, includes arotating seal member and an outlet port for delivering fluid to arotating component. A seal surface of the non-rotating seal member isbiased into fluid-tight engagement with the seal surface of the rotatingseal member, generally by a spring, media pressure, or other method,thus enabling a seal to be formed between the rotating and non-rotatingcomponents of the union. The seal permits transfer of fluid mediumthrough the union without significant leakage between the non-rotatingand rotating portions. Fluid medium passing through the rotary union maylubricate the engaged seal surfaces to minimize wear of the sealmembers. When a rotary union is used with non-lubricating media (such asdry air) or without any media, the engaged seal surfaces experience a“dry running” condition, which causes rapid seal wear due to lack ofadequate lubrication. Extended periods of dry running can cause severedamage to the seal members, thereby requiring expensive andtime-consuming replacement of one or both seal members.

High-speed machining equipment, such as computer-numerical-control (CNC)milling machines, drilling machines, turning machines, transfer lines,and so forth, use rotary unions to supply a medium directly to thecutting edge of a tool for cooling and lubrication in an arrangementthat is commonly referred to as “through spindle coolant.” A throughspindle coolant arrangement extends the service life of costly cuttingtools, increases productivity by allowing higher cutting speeds, andflushes material chips that can damage the work-piece or cutting toolaway from the cutting surfaces of the tool. Different work-piecematerials typically require different media for optimal productivity andperformance. For example, air or aerosol media may provide betterthermal control when machining very hard materials, while liquidcoolants may offer better performance when machining softer materials,such as aluminum. In addition, certain kinds of work may be performedmore effectively and less expensively without a through-spindle medium.

A variety of designs intended to avoid dry running with non-lubricatingmedia or no media are known. For example, rotary unions having sealsurfaces that disengage when opposing fluid pressures are present, suchas the arrangement disclosed in U.S. Pat. No. 5,538,292, can be complexand expensive to manufacture. Rotary unions having seal surfaces thatdisengage automatically in the absence of media, such as the arrangementdisclosed in U.S. Pat. No. 4,976,282, are less complex to manufactureand incorporate in a machine, but are prone to engagement of the sealsurfaces when non-lubricating media is used. Seal surfaces with specialgeometries for non-contacting operation with gases, such as thosedisclosed in U.S. Pat. Nos. 6,325,380 and 6,726,913, do not provideeffective sealing with liquid media. Similarly, seal surfaces withspecial geometries to distribute the medium evenly, such as the sealarrangement disclosed in U.S. Pat. No. 6,149,160, offer no advantagewhen non-lubricating media is used. Rotary unions that engage the sealsurfaces at all times, even with a reduced bias, such as the unionsdisclosed in U.S. Pat. No. 6,929,099, are prone to damage from dryrunning at high rotating speeds.

However, even with use of improved sealing and mechanisms to avoid dryrunning of unions, any union will eventually require repair orreplacement. Some machine operators may replace unions periodically toprevent a sudden loss in performance, or may operate a machine with aunion that requires replacement. Such and other measures typically havecostly consequences. Periodic inspections of unions are also timeconsuming and costly as unions are typically found within a machine andrequire effort by a technician to access them and assess theircondition.

BRIEF SUMMARY OF THE DISCLOSURE

The disclosure describes, in one aspect, a rotary union. The rotaryunion includes a housing having a fluid inlet, a rotating machinecomponent rotatably supported in the housing, a rotating seal memberassociated with the rotating machine component, a non-rotating sealmember slidably and sealably disposed within the housing adjacent therotating seal member, an expandable seal disposed between and sealablyengaging a bore in each of the non-rotating seal member and the housing,wherein the expandable seal includes two end portions, one of the twoend portions engaged to the non-rotating seal member and the other ofthe two end portions engaged to the housing, and an internal clampdisposed within an end portion of the expandable seal such that the endportion of the expandable seal is compressed between the internal clampand the bore of the housing.

In another aspect, the disclosure describes a rotary union that includesa housing having a fluid inlet, a rotating machine component rotatablysupported in the housing, a rotating seal member associated with therotating machine component, a non-rotating seal member slidably andsealably disposed within the housing adjacent the rotating seal member,an expandable seal disposed between and sealably engaging a bore in eachof the non-rotating seal member and the housing, the expandable sealincluding two end portions, one of the two end portions engaged to thenon-rotating seal member and the other of the two end portions engagedto the housing, an expandable ring disposed within an end portion of theexpandable seal such that the end portion of the expandable seal iscompressed between the expandable ring and the bore of the housing, anda second expandable ring disposed within an end portion of theexpandable seal such that the end portion of the expandable seal iscompressed between the second expandable ring and the bore of thenon-rotating seal member.

In yet another aspect, the disclosure describes a method formanufacturing a rotary union. The method includes slidably and sealablymounting a non-rotating seal member in a housing adjacent a rotatableseal member, mounting an expandable seal between a bore in each of thenon-rotating seal member and the housing, the expandable seal includingtwo end portions, one of the two end portions engaged to thenon-rotating seal member and the other of the two end portions engagedto the housing, and inserting an expandable ring within an end portionof the expandable seal such that the end portion of the expandable sealis compressed between the expandable ring and the bore of the housing.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a perspective view of a rotary union in accordance with thedisclosure.

FIG. 2 is section view of the rotary union shown in FIG. 1.

FIG. 3 is a perspective view, and FIG. 4A is an enlarged, detail view ofa seal in accordance with the disclosure; FIG. 4B is an enlarged, detailview of an alternative embodiment of a collar for a seal in accordancewith the disclosure.

FIGS. 5 and 6 are different views of a sensor module in accordance withthe disclosure.

FIG. 7 is a schematic view of a union monitoring system or arrangementof components in accordance with the disclosure.

FIGS. 8-10 are flowcharts for methods in accordance with the disclosure.

FIGS. 11 and 12 are perspective views of a rotary union in accordancewith the disclosure.

FIG. 13 is an enlarged, detail view of an expanding ring for use with anexpanding seal in accordance with the disclosure.

FIG. 14 is an outline view of an expanding ring in accordance with thedisclosure.

FIGS. 15 and 16 are partial, outline views of the expanding ring of FIG.14 shown in its natural and expanded conditions.

DETAILED DESCRIPTION

In the drawings, which form a part of this specification, FIG. 1 shows aperspective view of a rotary union 100, and FIG. 2 shows a section viewthrough the rotary union 100 to illustrate various internal components.It should be appreciated that in the exemplary embodiments shown herein,a rotary union is illustrated but the systems and methods described inthe present disclosure are equally applicable to any rotary device thatincludes stationary and fully or partially rotatable components insliding contact with one another. Examples of rotary devices, therefore,can include rotary unions or swivel joints, which are used to conveyfluids through fully or partially rotatable joints or components, andcan also include devices for connecting electrical leads across fully orpartially rotatable interfaces such as slip rings. In reference to theexemplary rotary union illustrated herein, the rotary union 100 includesa rotating seal member 102 and a non-rotating seal member 104 that isaxially moveable relative to a housing 106. A segmented conduit or mediachannel 112 extends through the housing 106, and also the rotating andnon-rotating seal members 102 and 104 respectively.

Portions of the media channel 112 are defined in different components ofthe rotary union 100 to provide a fluid passageway through the rotaryunion 100 when the rotating and non-rotating seal members 102 and 104are engaged. The media channel 112 may be selectively arranged tosealingly enclose fluids when the rotating and non-rotating seal members102 and 104 are engaged to one another, and be open for venting to theatmosphere when the rotating and non-rotating seal members 102 and 104are not engaged.

The rotating seal member 102, which is embodied here as a seal ringattached to the rotating machine component 108, but which mayalternatively be integrated with the rotating machine component 108, canbe any type of machine component such as a spindle on a CNC millingmachine. A mechanical face seal created when the rotating seal member102 is engaged with the non-rotating seal member 104 seals the mediachannel 112 for transferring a fluid medium from a fluid inlet 110 ofthe housing 106 to an outlet 111 formed at the end of the rotatingmachine component 108, as is known in the art. The rotating machinecomponent 108 has a bore 109 that defines a portion of the media channel112.

The non-rotating seal member 104 is slidably and sealingly disposedwithin a bore 128 of the housing 106. The structural arrangementpermitting sliding of the non-rotating seal member 104 relative to thenon-rotating machine component 110 enables the selective engagement anddisengagement of the non-rotating seal member 104 with the rotating sealmember 102, and compensates for axial displacement that may be presentbetween the rotating machine component 108 and the housing 106.

The selective variation of fluid pressure within the media passage 112during operation of the rotary union 100 yields net hydraulic forcesthat are applied to urge the moveable non-rotating seal member 104 tomove relative to the housing 106 such that a sealing engagement canoccur along an interface 114 between the rotating seal member 102 andthe non-rotating seal member 104. Extension of the seal member 104relative to the housing 106 and engagement of corresponding sealingsurfaces formed at opposing faces of the rotating seal member 102 andthe non-rotating seal member 104 create a fluid passage along the mediachannel 112. The non-rotating seal member 104 may be keyed into itsreceiving bore in the housing 106 to prevent its rotation, especiallywhen sealing engagement exists between the rotating seal member 102 andthe non-rotating seal member 104.

The housing 106 sealingly engages the non-rotating seal member 104, anddefines various hydraulic chambers therein for the selective engagementbetween the rotating and non-rotating seal members 102 and 104. Morespecifically, the housing 106 includes a stepped bore portion 116 thataccommodates therein and sealably engages one end of an expanding seal118, which is formed with a bellows portion 120 that is disposed betweenstraight portions 122 (also see FIG. 3 and the enlarged detail sectionsshown in FIG. 4A and FIG. 4B). The expanding seal 118 may be formed ofan elastic material such as rubber, TPE, a fluoroelastomer, and othermaterials, and includes rigid collars 124 along the straight portions122. The expanding seal 118 engages the stepped bore portion 116 at oneend, and a recess 126 formed in the non-rotating seal member 104 atanother end. When the non-rotating seal member 104 is urged by hydraulicforces to move towards engagement with the rotating seal member 102, theexpanding seal 118 expands in an axial direction as the bellows portion120 increases in length along a centerline 128 of the expanding seal118, which in the illustrated embodiment has a generally cylindricalshape that is disposed concentrically with the rotating machinecomponent 108 and the rotating seal member 102.

As can be seen in FIGS. 4A and 4B, the stepped bore portion 116 and therecess 126 form rounded or chamfered edges facing the expanding seal 118to help retain the seal in place and also to avoid possible damage ortears to the seal material during use. Specifically, these edges, whichare denoted as edges 130 in FIGS. 4A and 4B, have a radius of curvature,R, that generally matches a radius of curvature, R′, of an interface 132between the straight portions 122 and the bellows portion 120 on theexpanding seal 118 (see FIG. 3). The compatibility of the radii at thearea of contact between the interface 132 and the edges 130 ensures alow-stress contact between moving or deforming portions of the expandingseal 118, the housing 106 and the non-rotating seal member 104

During operation of the rotary union 100, the expandable seal 118 isgenerally retained in place because it axially constrained at both endsby the housing 106 and the non-rotating seal member 104. The expandableseal 118 is also radially retained in place through the engagement ofthe outer cylindrical surface of the straight portion 122 with an innercylindrical surface of the stepped bore portion 116. Such engagement maybe sufficient to maintain the expandable seal 118 in position duringoperation with no internal pressure, or positive pressure. However, ifthe media channel 112 is exposed to negative pressure (vacuum), such asmay be used to evacuate fluids within the media channel 112, thepossibility may exist that the expandable seal may elastically deform,at least temporarily, and especially in areas along the radially outercylindrical contact interfaces with the straight portions 122.

To ensure that continuous contact is present along the straightportions, the collars 124 are inserted internally in the straightportions 122. Each collar 124 forms a shaft section 134, which has ahollow cylindrical shape, and may optionally also include a ledge 135(shown in FIG. 4B), which extends radially outwardly relative to theshaft section. The ledge 135 may extend radially outwardly with respectto the shaft section 134 to an outer diameter that is larger than atypical inner diameter 138 of the media channel 112, or at least aninner diameter of a component that surrounds the expandable seal 118such as the non-rotating seal member 104 and an opening 140 in thehousing.

When inserted into each straight portion 122, each collar may beoriented such that the ledge 135 is disposed on the side of the bellowsportion 120. In the illustrated embodiment, where no ledge is included,the collars 124 are inserted fully into each respective straight portion122 such that they fully cover, in an axial direction, an engagementregion of the straight portions 122 with the housing or non-rotatingseal member. When the expandable seal 118 is installed in the rotaryunion 100, and the collars 124 are in position, each collar 124 is sizedto impart a preselected radially outward and compressive force into thestraight portion 122 of the expandable seal 118 to provide a sealingengagement between the two ends of the expandable seal 118 and therespective mating component, which as can be seen in FIGS. 4A and 4Bincludes the housing 106 and the non-rotating seal member 104. Whenlubricants are used in the media channel 112, which may enter along theinterfaces between the expandable seal 118 and the components in whichit is installed, an axial force may tend to push either end of the sealaxially with respect to its mating components. To limit such slidingconditions, the collar 12.4 acts to limit the axial motion of thestraight portions 122.

An alternative embodiment for the collar 124 is shown in FIG. 13, whereboth collars 124 have been replaced by a respective internal clampembodied as an expanding ring 700. An outline view of the expanding ring700 is shown in FIG. 14, and two partial outline views of the expandingring 700 are shown in FIG. 15, where the expanding ring 700 is in anatural or retracted condition, and in FIG. 16, where the expanding ring700 is in an enlarged or expanded position. In reference to thesefigures, the expanding ring 700 has a generally hollow cylindrical shapethat includes a segmented wall 702. In the illustrated embodiment, thesegmented wall 702 is made from three arcuate wall segments 704 that areresiliently connected to one another by resilient structures 706. Theresilient structures 706, as will be described hereinafter, flexiblyand/or resiliently connect the arcuate wall segments 704 to one anothersuch that, when the expanding ring 700 is subjected to an axial loadalong its centerline 708, the resilient structures 706 translate theaxial load into a tangential load along a periphery of the wail 702 toexpand the periphery by allowing the arcuate wall segments 704 to movein a radially outward direction and increase the overall outer diameterof the expanding ring 700. Similarly, when the axial loading is removedor reduced, the resilient structures 706 permit a contraction of thearcuate wall segments 704 towards one another in a radial direction to,thus, restore or reduce the overall outer diameter of the expanding ring700 to its original, natural dimension.

In the illustrated, exemplary embodiment, the expanding ring 700 is madeof a metal such as steel. The structure of the expanding ring 700 ismanufactured by cutting various segments, for example, by laser cutting,into a section or length of tubular material. As shown, the expandingring 700 is made from three arcuate wall segments 704 that areinterconnected by three resilient structures 706, but a different numberof arcuate wail segments and resilient structures may be used.

Each arcuate wall segment 704 extends over a chord of about 120 degreesaround a periphery 710 of the expanding ring 700. Each resilientstructure 706 is made by two leaf spring portions 712 that are connectedto one another by a synchronizer bar 714. Each resilient structure 706includes two leaf spring portions 712 having an axial thickness that isabout equal to a wall thickness of the arcuate wall segments 704 and aredisposed at either axial end of the expanding ring 700. Each leaf springportion 712 includes two legs 716 that meet at an apex 718. The legs 716are connected on one end with a corner of an adjacent arcuate wallsegment 704 and at another end to the apex 718. While the material thatmakes up the legs 716 is integrally formed with the material that makesup the apex 718 and also the material that makes up the adjacent wallsegment 704, elastic deformation of the material around each end of eachleg 716 provides a pivoting connection between each leg 716 and thecorresponding apex 718 and adjoining arcuate wall segment 702.Similarly, each synchronizer bar 714 is connected between two apices 718such that each apex 718 provides a connection that allows the legs 716and the synchronizer bar 714 to pivot relative to one another.

In a natural or unloaded condition, the legs 716 are disposed at anobtuse angle, α, relative to one another in a “V” or chevronconfiguration. As shown in FIG. 14, all three sets of legs 716 areoriented in the same direction in this respect on a given expanding ring700. When installed in a rotary union, as shown in FIG. 13, the twoexpanding rings 700 may be installed such that the apices 718 of theinnermost resilient structures 706 are closest to one another or, stateddifferently, the chevron shapes of the legs 716 in both rings 700 openaway from each other.

The orientation of the legs 716 in the expanding ring 700 advantageouslyprovides a directional reaction to an application of axial force ontothe ring such that expansion of the ring results from the application ofan axial load in one direction, and contraction of the ring results fromthe application of an axial load in the opposite direction. In theembodiment shown herein, expansion of the ring will result when an axialforce is applied in a direction tending to push the two rings 700 awayfrom one another, in the arrangement shown in FIG. 13, or in a directionfrom the top towards the bottom of the ring in the orientation shown inFIG. 14. When an axial force is applied in a direction, F, as shown inFIG. 14, along the axis 708, the ring will expand. Stated differently,if a hydraulic pressure difference is applied on an inner surface of thering 700, the ring will expand and react by providing an axial forcetending to push the rings together in the orientation shown in FIG. 13.The reaction of this axial force will thus tend to push the ends of theexpandable seal 118 apart. This application of force is due to the shapeand arrangement of components in the resilient structures 706.

At the natural condition of the ring 700, as shown in FIG. 15, both setsof legs 716 of a resilient structure 706 are disposed at the angle, α,and the synchronizer leg 714 is axially displaced relative to the axiallength, L, of the wall 702. When internal, hydraulic or pneumaticpressure is applied to the wall 702, or when the expanding seal 118 isextended, an axial load is created that tends to expand the ring 700. Asthe ring 700 expands, an angle between the leaf spring portions 712 willincrease or, stated differently, the angle between the legs 716 willincrease from the natural angle, α, to an increased angle, β, as shownin FIG. 16.

In the expanded condition, the angular displacement between the pairs oflegs 716 at each apex 718 of any one resilient structure 706 will be thesame because of the connection between the two apices 718 provided bythe synchronizer bar 714. Further, a gap 720 between the edges of thesynchronizer bar 714 that face the arcuate wall segments 704 and theedges of the arcuate wall segments 704 that face the synchronizer bar714 will increase proportionally to the cosine of the difference betweenthe angle β and the angle α. Because the increase in the gap will alsoincrease the overall periphery 710 of the ring, the increase in theperiphery can be expressed by the following relation:

δP=f(cos(β)−cos(α)C

where δP is a change in the periphery 710 and C is here considered aconstant that accounts for the constant, π, and also certain materialproperties and geometrical relations between the various materialcomponents, but it should be appreciated that, for larger dimensionrings, the quantity of C may not be constant and may depend on theperiphery of the ring and other dimensions.

It should be appreciated that the expanding ring 700 may also be used ina locked, expanded position, in which the resilience of the resilientstructures 706 is sacrificed in favor of a constant, gripping forceprovided by an expanded periphery 710, especially in applications wherean increased radial retaining force is desired. In such a condition,upon installation or initial service of the ring 700, an axial force maybe provided that pushes the resilient structures 706 past their elasticdeformation limits and plastically deforms the material at the junctionsbetween the legs 716 and their surrounding components, which essentiallywill drive the angle, β, shown in FIG. 16 closer to an angle of 180degrees. In this condition, the ring 700 will assume an over-centerlocked state and will attain its maximum outer diameter. When using thering 700 in the over-center locked position, the ring 700 serves as aninternal clamp used to retain elastic materials such as rubber sleevesor hoses engaged within a bore formed in a component by applying a forcein a radially outward direction tending to compress the material of thearticle being retained from within.

Depending on the uncompressed length of the expandable seal 118 alongits centerline, the expandable seal 118 can also be used to provide apre-load or pre-tension to the rotating and non-rotating seal members102 and 104. Such pre-tension may be augmented or supplemented in astatic fashion by springs 136, which are illustrated in the exemplaryembodiment of FIG. 4A and are shown as compression springs. Morespecifically, where certain rotary unions may include a spring tendingto push the seal members into contact with one another, the spring andother secondary seals can be eliminated and replaced or assisted, as inthe illustrated embodiment, by the expandable seal 118, which fulfillsthe role of maintaining a fluid seal as the non-rotating seal member 104moves with respect to the housing 106, and also can be selected suchthat it fulfills the role of pre-tensioning the seal members, i.e.pushing the seal members towards a seal engagement direction towards oneanother in an elastic fashion, if the length of the expandable seal 118is selected to be larger than the axial opening for the seal that isprovided. Dynamically, when a fluid under positive gage pressure ispresent in the media channel 112, the biasing force of the expandableseal 118 may be further augmented by a hydraulic force tending to expandthe seal. In the illustrated embodiments, the expandable seal 118includes a bellows with two convolutions, or bellows that are generallyM-shaped, but a single or more than two convolutions can be used.

In reference now back to FIGS. 1 and 2, the rotary union 100 furtherincludes two roller hearing assemblies 142 disposed between the housing106 and the rotating machine component 108. More specifically, thehousing 106 forms a bearing region 144 that accommodates one or morebearings 146, two of which are shown in the illustrated embodiment. Thebearings 146 are shown as ball bearings, each including an outer race148, an inner race 152, and a plurality of balls 154 disposedtherebetween. Each outer race 148 and inner race 152 is formed as aring, where the outer race 148 radially engages an inner generallycylindrical surface 156 of the bearing region 144 of the housing 106,and where the inner race 152 engages an outer generally cylindricalsurface 158 of the rotating machine component 108. In the illustratedembodiment, the inner surface 156 of the bearing region 144 is formed ina metal insert 159 that is inserted and connected to the otherwiseplastic housing 106.

The bearings 146 are axially constrained within the inner generallycylindrical surface 156 by C-rings 160. When the C-rings 160 aresequentially removed, the entire assembly of rotating and non-rotatingcomponents and seal members can be removed from the housing 106 througha front opening 162 to advantageously facilitate assembly, disassemblyand service of the rotary union 100. An inner C-ring 160 is disposedcloser to the non-rotating seal member 104 and is engaged along an innerdiameter thereof around the rotating machine component 108. An outerC-ring 160, which is disposed closer to the front opening 162, isengaged along an outer diameter thereof within the inner generallycylindrical surface 156 of the bearing region 144 of the housing 106.The housing 106 further forms one or more drain opening(s) 164 adjacentthe sealing interface between the rotating seal member 102 and thenon-rotating seal member 104.

A rotor 166, which axially occupies a space between the inner bearing146 and an annular end-surface of the bearing region 144, has agenerally disc shape and is disposed around an inner end of the rotatingmachine component 108. The rotor 166 includes one or more magnets 168disposed at regular angular intervals around a periphery thereof. Anouter ledge 170 formed on the rotating machine component 108, incooperation with the bearings 146 and the rotor 166, help to axiallyconstrain and rotatably mount the rotating machine component 108 and therotor 166 with respect to the housing.

The rotary union 100 described herein may be manufactured and assembledby various methods. In the illustrated embodiment, the main componentsof the rotary union 100, such as the housing 106, the rotating machinecomponent 108 and, possibly, the rotor 166, are manufactured by use ofplastic materials, which may be formed in any suitable way, including byuse of three-dimensional printing machines. Metal inserts 107 may beadded at the fluid interfaces of the housing 106. Alternatively, anddepending on the operating environment of the rotary union, the type andtemperature of the fluid that will at times occupy the media channel112, some or all of these and other components may be manufactured usingdifferent materials such as metal and different manufacturing methods.

Relevant to the present disclosure, the rotary union 100 furtherincludes a sensor array 200 disposed in a pocket 202 that is defined inthe housing 106 and enclosed by a cover 204, as shown, for example, inFIGS. 1 and 2. In the illustrated embodiment, the pocket 202 is shown tobe fluidly separated or isolated from the media channel when therotating and non-rotating seal members 102 and 104 are in contact.Further, the sensor array 200 has a portion that protrudes from thepocket and overlaps axially one of the drain openings 164 and also aninterface of the rotating and non-rotating seal rings 102 and 104. Thesensor array 200 in the illustrated embodiment is a fully-operativesensor array that includes one or more sensors arranged on a substrate,which also includes power and communication devices. In general, anytype of fully-operative or independent sensor array may be used.Exemplary illustrations of the sensor array 200, which inhabits acircuit board 206, is shown from both sides in FIGS. 5 and 6. Inreference to FIG. 5, which shows a front side of the array 200, thesensor array includes various components, including an antenna 206, aradio frequency connector 208, an accelerometer 209, two infrared (IR)temperature sensors 210 and 211, a motion sensor 212, a humidity sensor213, a micro-control unit (MCU) 214, but other sensors and devices maybe used. As shown, the first IR temperature sensor 210 is disposed tomeasure a temperature of the housing 106, and the second IR temperaturesensor 211 is disposed adjacent the non-rotating seal member 104 andconfigured to measure a temperature of the rotating and/or non-rotatingseal members 102 and 104. Additional sensors may include fluid pressuresensors, strain gauges, and other sensors used for detecting, directlyor indirectly, a pressure of the fluid media present in the mediachannel.

On its back side, as shown in FIG. 6, the sensor array 200 includes amemory storage device 216, a magnetic pickup sensor 218, a power storagedevice 220, and other devices. These various devices and sensors may beused to advantageously detect, track, monitor, alert, notify and infervarious operating parameters of the rotary union that can he used todetermine the operating state and general operational parameters whichcould be used to determine the “health” of the rotary union 100 and themachine in which the rotary union 100 is operating. Data gathered couldalso be used to compare, analyze and optimize operations.

In one contemplated embodiment, the magnets 168 disposed along the rotor166 may be used to generate a rotating magnetic field during operationof the union 100, which can be used to generate electrical power at acoil to charge a power storage device 220 or, in general, to power thesensor array 200. The coil, which can be embodied along with themagnetic pickup sensor 218, or another equivalent electrical component,can provide a solution for powering the sensor array 200 as well asrecharging the battery, thus eliminating the need to periodically changebatteries. Along these lines, other power sources may be used such aspiezoelectric elements operating to generate electrical potential whenthe union vibrates, photovoltaic cells for applications where the unionis exposed to natural or artificial lighting, and the like. In analternative embodiment, the power storage device 220 may be embodied asa battery, which can be replaced when its power has depleted, or it canalso be a connection for a wired supply of electrical power from anexternal source.

More specifically, various signals indicative of the physical conditionsof the rotary union and its surrounding environment can be generated bythe various sensors in the sensor array 200 and communicated to the MCU214 for processing and/or transmission to an external receiver for relayto a machine operator or monitor. In the exemplary embodiment shown anddescribed in the present disclosure, the antenna 206 and/or radiofrequency connector 208 may be used to effect wireless communication ofinformation to and from the sensor array, as will be described belowrelative to FIG. 7. Regarding the various sensor signals that can beused to determine or monitor rotary union health, the temperature sensor210 may be used to monitor the temperature of, or the space or materialimmediately around, the rotary union 100 as an indication of thecondition of the rotating and non-rotating seal members 102 and 104.Additionally, this or other sensors or sensor arrays may be used tomonitor and record fluid pressure and/or fluid temperature of theworking media. In this respect, dry running or excessive friction at thesealing interface during operation will raise the temperature of theseal members relative to the housing, and thus heat the surroundingstructures in the rotary union, which will cause an increase in thetemperature sensed by the temperature sensor 211, which will bereflected in the temperature signal provided to the MCU 214 as atemperature difference that can be used to determine a seal failure.

Similarly, other sensors may be used to determine the operating state ofthe rotary union 100. The humidity sensor 213 may be used to sense thepresence or an increase in humidity, which can be an indication of sealleakage. In one embodiment, to avoid false-positive leakage signals, theMCU 214, in the presence of cold fluid passing through the media channel112 in a humid environment, may detect humidity from condensation andnot signal a leakage unless additional indications of a leakage areprovided, for example, a heating of the seal interface and fluid motionthrough at least one of the drain openings. The magnetic pickup sensor218 may sense the magnets 168 (FIG. 2) as they pass by the sensor 218while the rotary union 100 operates and the rotor 166 (FIG. 2) isrotating to provide an indication of the speed of rotation, and also ofthe number of revolutions the rotary union has undergone, which inconjunction with a counter can provide an indication of the service lifeof the rotary union 100. The accelerometer 209 may sense vibration inthe rotary union 100 to provide an indication of the balance and, thus,the structural state of the rotating components within the rotary union100 and those components connected to the union to detect structuralissues associated with the rotary union 100 or the machine in which therotary union 100 is installed. Other sensors may also be used to monitorand record flow rate and/or pressure of the fluid media.

The various operating parameter signals generated by the sensorsdiscussed above, and possibly additional or different signals generatedby other sensors, may be continuously transmitted in real time, or atleast during operation of the rotary union 100, to a control center 300,as shown in the schematic diagram shown in FIG. 7. FIG. 7 shows two outof numerous other possible embodiments for the wireless communication ofinformation between the rotary union 100 and, specifically, the sensorarray 200, and the control center 300. In the illustrated, exemplaryembodiments, two options are shown.

In a first option, shown on the left side of FIG. 7, the antenna 206(shown in FIG. 5) of a rotary union 100 installed in a machine 301 isconfigured to transmit and receive information either via an appropriatewireless network, and/or through a wired connection. In the illustratedembodiment, a local area network (LAN) 304 is used to communicate with amobile computing device 302, but any other wireless network such as awide area network (WAN), or a direct will connection may be used. Themobile computing device 302 may be embodied in any known type of device,including a Smartphone, tablet, portable computer, or wireless signalgateway device. The mobile computing device may be a handheld device ormay alternatively be a device that is integrated with, or part of, alarger machine such as the machine 301 into which the rotary union 100is installed and operating. In addition to the wireless connection tothe network 304, the mobile computing device further includes anInternet connection 306 that connects the mobile computing device 302 tothe Internet 308. The Internet connection 306 may be direct, forexample, via a cellular data connection, or indirect such as over wifi.In one embodiment, the functionality of the control center 300 may beintegrated locally into the mobile computing device 302, thus obviatingthe need for further connections. As can be appreciated, the Internet308 may be part of the world wide web, or may alternatively be adistributed network operating in a cloud configuration across multiplelocations simultaneously. In this arrangement, the control center 300 isconfigured to exchange information with the rotary union 100 via theInternet 308 by use of a dedicated connection 310. Because of the rangelimitations of certain types of networks, and also the flexibility ofusing a mobile computing device, the first option may be well suited forsmaller installations where a handful of machines 301 are installed inrelatively close proximity to one another. For larger installations, asecond option may be used, which is shown on the right side of FIG. 7.

In the second option, the antenna 206 (shown in FIG. 5) of a rotaryunion 100 installed in a machine 311 is configured to transmit andreceive information wirelessly in a dedicated low-power, local areanetwork 312 or, in an alternative embodiment, a wide area network. Thelocal area network 312 is a low-cost, low-power, wireless mesh networkstandard targeted at wide development of long battery life devices inwireless control and monitoring applications. Information over thenetwork 312 may be managed by a dedicated gateway device 314, which maybe a standalone device handling one or more rotary unions 100 operatingin the same or multiple machines 311. The gateway traffics informationfrom the network 312 to an Internet connection 216, which is connectedto the Internet 308 and thus to the control center 300. Alternatively,the connection to the control center 300 may be made directly with therotary union 100 in a configuration of the union that is capable ofdirect Internet connection. Apart from these two options, additionalembodiments can include a direct wifi, wired network, or cellular datanetwork connection between the rotary union 100 and the control center300.

In the information exchange systems shown in FIG. 7, various diagnosticand monitoring functions relative to the rotary union 100 can berealized. For example, customized mobile applications operating in themobile computing device 302, or specialized computer applicationsoperating in computers located at the control center 300, can be used tomonitor the operation of specific rotary unions 100 to assess theiroperating state either locally or remotely. Such applications canprovide further advantages such as automating rotary union re-orders, toreplace unions that are determined to be nearing their service life byuse of these systems, providing troubleshooting guides for unusualoperating conditions detected by the sensor arrays 200, and evenproviding a live connection to a customer or technical specialist viachat or phone connection when issues are encountered.

A flowchart for a method of operating a rotary union is shown in FIG. 8.The method includes operating the rotary union in a machine at 402. Inaccordance with the disclosure, the rotary union includes a sensor arraythat is integrated with the rotary union and includes wirelesscommunication capability. In an optional embodiment, operation of therotary union includes using a rotational motion of the union to generateelectrical power to operate the sensor array at 404. The method ofoperating the union further includes sensing one or more operatingparameters of the rotary union using one or more sensors of the sensorarray at 406. Each of one or more sensors generates a sensor signal at408, which sensor signal is received and/or processed by a control unitat 410. The control unit 410 effects a transmission of the sensorsignal(s) to a control center at 412. In one embodiment, the controlunit 410 is further configured to store the sensor signals using anon-board memory storage device. The stored sensor signals, which mayalso include time-stamp, date and other information, may be availablefor later retrieval from the control unit. Moreover, the control center412 may be a centrally located processing center for one or more unions,and additionally or alternatively may be a mobile electronic device thatis present in close physical proximity to the rotary union, eitherpermanently or transiently as an operator passes by the rotary unioncarrying the mobile electric device, for example, during a liveinspection of the operating state of the union.

The control center receives and processes the sensor signal(s) 414 todiagnose an operating state of the rotary union at 416. In the event ofan abnormal operating condition, which is determined at 418, the controlcenter may initiate a mitigation process at 420, which includes but isnot limited to informing a machine operator of the abnormal operatingcondition or, depending on the preferences of the operator,automatically recommend to the operator and/or automatically initiate,with prior authorization of the machine operator, shipment of areplacement rotary union. In addition, the determination at 418 mayautomatically prompt or initiate creation and transmission of an alertto a subscriber, informing the subscriber of the operating state of theunion.

A flowchart for a method of detecting a seal failure in a rotary deviceis shown in FIG. 9. The method includes operating the device at 502,which includes operating at least two temperature sensors and acontroller. The first temperature sensor is configured to measure atemperature associated with a mechanical interface between the rotatingand the non-rotating members, for example, by measuring the bodytemperature of the rotating and/or non-rotating members at 504. Themembers may be seal rings or may alternatively be electrical connectionrings when the rotary device is embodied as a slip ring. In oneembodiment, the temperature at 504 is acquired using an IR sensor. Thesecond temperature sensor is configured to measure a temperatureassociated with the housing of the rotary device, for example, a bulkhousing material temperature at 506. The controller receives the firstand second temperature readings at 508, and compares the bodytemperature to the mechanical interface temperature at 510. When thefirst and second temperatures are within a predetermined range of oneanother at 512, the monitoring continues. When the first temperatureexceeds the second temperature by a predetermined amount at 514, thecontroller may signal a fault at 516.

A flowchart for a method of detecting a leak, which avoids falsepositive leak indications, is shown in FIG. 10. The method includesoperating the rotary device at 602, which includes operating a leaksensor, a humidity sensor, a fluid temperature sensor, a housingtemperature sensor and, optionally, a motion sensor and also an IRtemperature sensor. The leak sensor monitors for presence of fluid at adrain passage at 604, the humidity sensor monitors ambient humidity at606, the fluid temperature monitors fluid media temperature 608 that ispresent in the media channel, the housing temperature sensor measuresthe temperature of the housing at 610, and the IR temperature sensormeasures a temperature at the interface between the rotating andnon-rotating seal members at 612. The motion sensor may optionallymeasure vibration of the rotary union. All signals are provided to thecontroller, which combines the various sensor signals into a set at 614,and compares the set to one or more predefined sets of conditionspresent in memory at 616. When the set matches a leak condition setpresent in memory, the controller signals a fault at 618, or otherwisecontinues monitoring the various parameters as previously described.

The sets present in memory also include sets determined to be falsepositives, even if the leak sensor provides a leak indication, due tooperating effects. For example, in high ambient humidity of a unionoperating with a cold fluid, which also cools the housing, condensationmay form around the leak sensor without an actual leak being present.The predefined sets stored in memory may, for instance, indicate whetherthe temperature of the union during operation is below a dew point forthe given ambient humidity, in which case, without a further indicationof failure, it may be presumed that liquid water is condensing on theunion rather than leaking from within the union. Accordingly, a leaksignal may be provided under condensation circumstances only if anotherfailure indication is also present, for instance, an overheating sealinterface, excessive vibration of the union, and the like.

All references, including publications, patent applications, technicaldocumentation and user manuals, patents, and other material cited hereinare hereby incorporated by reference to the same extent as if eachreference were individually and specifically indicated to beincorporated by reference and were set forth in its entirety herein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

1. A rotary union, comprising: a housing having a fluid inlet; arotating machine component rotatably supported in the housing; arotating seal member associated with the rotating machine component; anon-rotating seal member slidably and sealably disposed within thehousing adjacent the rotating seal member; an expandable seal disposedbetween and sealably engaging a bore in each of the non-rotating sealmember and the housing, the expandable seal including two end portions,one of the two end portions engaged to the non-rotating seal member andthe other of the two end portions engaged to the housing; and aninternal clamp disposed within an end portion of the expandable sealsuch that the end portion of the expandable seal is compressed betweenthe internal clamp and the bore of the housing.
 2. The rotary union ofclaim 1, further comprising a second internal clamp disposed within anend portion of the expandable seal such that the end portion of theexpandable seal is compressed between the second internal camp and thebore of the non-rotating seal member.
 3. The rotary union of claim 1,wherein the internal clamp is configured to compress the end portionunder all operating conditions of the rotary union.
 4. The rotary unionof claim 1, wherein the internal clamp is configured to compress the endportion at a variable degree depending on a fluid pressure of mediawithin the rotary union.
 5. The rotary union of claim 1, wherein theinternal clamp includes at least one arcuate wall segment and at leastone resilient structure disposed between two adjacent ends of the atleast one arcuate wall segment.
 6. The rotary union of claim 1, whereinthe internal clamp includes a plurality of arcuate wall segments and aplurality of resilient structures disposed, one each, between adjacentends of two adjacent arcuate wall segments around an entire periphery ofthe internal clamp.
 7. The rotary union of claim 6, wherein eachresilient structure includes: two leaf spring portions disposed, oneeach, at either axial end of the internal clamp; and a synchronizer barconnected between the two leaf springs.
 8. The rotary union of claim 7,wherein each leaf spring portion includes two legs connected to oneanother at one end to an apex, and connected at each respective secondend to an adjacent arcuate wall segment edge, and wherein thesynchronizer bar is connected between two apices.
 9. The rotary union ofclaim 8, wherein the legs are disposed in a V-configuration that definestherewithin an angle, the angle being configured to increase as theinternal clamp expands to increase its outer diameter.
 10. The rotaryunion of claim 1, wherein the internal clamp is configured to assume anover-center locked position when displaced axially,
 11. A rotary union,comprising: a housing having a fluid inlet; a rotating machine componentrotatably supported in the housing; a rotating seal member associatedwith the rotating machine component; a non-rotating seal member slidablyand sealably disposed within the housing adjacent the rotating sealmember; an expandable seal disposed between and sealably engaging a borein each of the non-rotating seal member and the housing, the expandableseal including two end portions, one of the two end portions engaged tothe non-rotating seal member and the other of the two end portionsengaged to the housing; an expandable ring disposed within an endportion of the expandable seal such that the end portion of theexpandable seal is compressed between the expandable ring and the boreof the housing; a second expandable ring disposed within an end portionof the expandable seal such that the end portion of the expandable sealis compressed between the second expandable ring and the bore of thenon-rotating seal member.
 12. The rotary union of claim 11, wherein theexpandable ring is configured to compress the end portion under alloperating conditions of the rotary union.
 13. The rotary union of claim11, wherein the expandable ring is configured to compress the endportion at a variable degree depending on a fluid pressure of mediawithin the rotary union.
 14. The rotary union of claim 1, wherein theexpandable ring includes three arcuate wall segments and three resilientstructures disposed symmetrically around a periphery of the expandablering in alternating order.
 15. The rotary union of claim 14, whereineach resilient structure includes: two leaf spring portions disposed,one each, at either axial end of the internal clamp; and a synchronizerbar connected between the two leaf springs.
 16. The rotary union ofclaim 15, wherein each leaf spring portion includes two legs connectedto one another at one end to an apex, and connected at each respectivesecond end to an adjacent arcuate wall segment edge, and wherein thesynchronizer bar is connected between two apices.
 17. The rotary unionof claim 16, wherein the legs are disposed in a V-configuration thatdefines therewithin an angle, the angle being configured to increase asthe internal clamp expands to increase its outer diameter.
 18. Therotary union of claim 11, wherein the internal clamp is configured toassume an over-center locked position when displaced axially.
 19. Amethod for manufacturing a rotary union, comprising: slidably andsealably mounting a non-rotating seal member in a housing adjacent arotatable seal member; mounting an expandable seal between a bore ineach of the non-rotating seal member and the housing, the expandableseal including two end portions, one of the two end portions engaged tothe non-rotating seal member and the other of the two end portionsengaged to the housing; and inserting an expandable ring within an endportion of the expandable seal such that the end portion of theexpandable seal is compressed between the expandable ring and the boreof the housing.
 20. The method of claim 19, further comprisingpermanently locking the expandable ring in an over-center lockedposition by axially displacing at least a portion of the expandablering.